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I installed Steeroids for about 10 years and added a $25 used Hydroboost about 5 years later. Everything worked fine until last year when I gradually lost power steering assist.
After reading about 100 CF threads, doing all the tests and replacing one component at a time (in low to high cost order. Now, 8 months later, I have new EVERYTHING: Hydroboost ("'68-'82 C3 Chevy Corvette Hydroboost and mount", master cylinder (aluminum), new rack & pinion unit, high volume power steering pump, power steering flow control valve, etc. EVERYTHING!
The problem is, neither the power steering nor power brakes work. The brake pedal is pushing on rock...no give at all. I increased power steering flow from 1.8 or so gph to 3 gph according to Jim Shea's papers with a power steering fluid cooler in case I have too much flow. I get a little assist to both for a very short drive before losing assist to both.
I read a couple of threads that mention the booster rod that goes into the master cylinder. I haven't measured that or tried spacers between the booster and master cylinder. Is that worth checking? What else could cause these problems?
Have you done any pressure tests? P/S requires about 700 psi. I'm unfamiliar with the required pressure for the hydroboost. Is your system set-up t-ed to allow equal pressure to both components or is the brake circuit downstream from R&P using the return circuit pressure? It sounds like all your pressure is being returned to sump. Try isolating just the P/S circuit to see if that works. T
I have brake / steering problems with my hydroboost set up! I am thinking it is the PS pump. Where did you get a high volume unit? I am ready to rip the sh*t off!
I have brake / steering problems with my hydroboost set up! I am thinking it is the PS pump. Where did you get a high volume unit? I am ready to rip the sh*t off!
Don't rip it off (yet). Both Steeroids and Hydroboost were GREAT when they worked.
There is a C3 Technical Forum Sticky Thread titled "Power steering needs some help???" Read that first before you buy more parts. One of the problems you may have is inadequate flow, not pressure. Read the posts from Jim Shea in that sticky thread.
I increased the flow from my pump but still no cigar. I'm thinking that ps fluid is not bypassing the Hydroboost to the Steeroids. I just don't know enough about how Hydroboost works to figure out a cause and solution. I think it has something to do with "brakes always on hard".
I have brake / steering problems with my hydroboost set up! I am thinking it is the PS pump. Where did you get a high volume unit? I am ready to rip the sh*t off!
After having a couple of pump failures, I went with KRC and pump problems are a thing of the past. T
I just met with a few guys from our car club at a Back To The 80's car show. Two of them with 80's cars (IROC Camaro & Firebird Trans Am) with Hydroboost had to shorten the actuator rod in the Hydroboost.
In a CF thread from the end of last year (Hydroboost clevis to brake pedal issue, CF member 7T1vette said, there should be some clearance between the actuator rod and master cylinder, but not much (0.020).
CF member Dub said,
"Measuring the depth of the master cylinder and using the contact surface or what ever is needed to achieve a measurement...and doing simple math...a person can find that IF they have the adjustment bolt (for example) 1/32" shorter. Then logic would dictate...that due to the length of the brake pedal in relation to the pivot point of the brake pedal...the pedal will move 'X' before it makes contact with the plunger in the master cylinder.
So...this is where you make your adjustments and you can fine tune your brakes accordingly."
Member '75 said,
"The hydroboost[er] requires that the pedal rod is returned all the way when your foot is off the pedal, so if the pedal is hitting the upper bump stop before the booster is completely relaxed..., it could make it twitchy or cause heat in the power steering fluid because the pump is trying to make pressure to give brake assist. That is not where the "free play" in the pedal comes from.
The free play in the pedal is determined by how much the pedal travels before the master cylinder closes off the brake fluid return port. If the push rod from the booster going into the master cylinder is too short, you will have lots of pedal travel before you begin to have brakes. Too long of a rod there will make it so the brakes don't fully release, the brake fluid return port is blocked inside the master cylinder. In this case the brakes will overheat due to residual pressure build up and eventually lock up."
This make sense. I'm going to remove the mc from the Hb and measure the mc indent and the Hb rod projection and decide what to do next based on these measurements.
Make damn sure you did not cross the pressure lines, the HB has a definate input port from the pump, and the output to the rack....make damn sure your lines are hooked that way,....also, I hear reports about using a T fitting to return to the pump, it is stated to use two lines into the pump housing, I have a serp drive from a '88-91 vette on my '72 and so the p/s res. is on the frame, and the T fitting I used feeds the one port to the res.....simple setup, really....and been fine for many years now....
Mr Vette, yeah I need to check that. I had the HB installed for me. Excellent point. I did not see anything kinked and it worked at speed, so I assumed it was all good. Thanks for the tip.
If it worked fine and then started acting up then I don't think its going to be the rod.
I have had the check valve in the outlet of the rack fail and lodge in the fitting, this was very hard to trouble shoot and to find.
Did you make any changes prior to it starting to act up?
Neal
The new HB and MC have never worked. My original setup work well for a few years and then went out shortly after I switched to Wilwood brakes last summer.
After consulting with SpeedDirect and doing all the diagnostics they recommended, I replaced the PS pump, then the R&P unit. It still didn't work, but then there wasn't any power assist for the brake either.
I removed the original $25 salvage yard HB unit and discovered it was badly corroded inside, so I bought a new one. The original MC wasn't returning after braking, so I replaced that too.
So I ended up with all new pb and ps components that haven't worked yet. So, did you make any changes prior to it starting to act up? Yup, everything was changed over the past 10 months.
The new HB and MC have never worked. My original setup work well for a few years and then went out shortly after I switched to Wilwood brakes last summer.
After consulting with SpeedDirect and doing all the diagnostics they recommended, I replaced the PS pump, then the R&P unit. It still didn't work, but then there wasn't any power assist for the brake either.
I removed the original $25 salvage yard HB unit and discovered it was badly corroded inside, so I bought a new one. The original MC wasn't returning after braking, so I replaced that too.
So I ended up with all new pb and ps components that haven't worked yet. So, did you make any changes prior to it starting to act up? Yup, everything was changed over the past 10 months.
Did you replace the lines? You have braided steel don't you? I have seen those collapse inside before and block flow.
Make damn sure you did not cross the pressure lines, the HB has a definate input port from the pump, and the output to the rack....make damn sure your lines are hooked that way,....also, I hear reports about using a T fitting to return to the pump, it is stated to use two lines into the pump housing, I have a serp drive from a '88-91 vette on my '72 and so the p/s res. is on the frame, and the T fitting I used feeds the one port to the res.....simple setup, really....and been fine for many years now....
I don't think mine are crossed because I THINK I plumbed the new HB like the old one, which worked for years.
HOWEVER, just be sure, here are 2 pictures of the new HB unit, one as installed (minus the 90 deg return fitting) and the other rotated 180 to see the ports.
The hose from the pump is attached to the port with the white plug and the hose to the Steeroids is attached to the port with the green plug. Correct?
You mention the brake peddle is rock hard, is this with the car running and off or just with the car running?
If the lines to the R&P are crossed it will cause the pump to see max pressure and the peddle will be rock hard. There is a check valve in the outlet of the rack that will cause the blockage in the system if plumbed wrong.
I don't think mine are crossed because I THINK I plumbed the new HB like the old one, which worked for years.
HOWEVER, just be sure, here are 2 pictures of the new HB unit, one as installed (minus the 90 deg return fitting) and the other rotated 180 to see the ports.
The hose from the pump is attached to the port with the white plug and the hose to the Steeroids is attached to the port with the green plug. Correct?
The white port is pressure from pump, green to rack, and return to res.....ehhh.....already have correct answer above...
06-16-2017, 10:59 PM
Hydoboost+Steeroids: no assist to either!!!
